Flat light-emitting elements may be implemented, in particular, in the form of electroluminescent layers, as light-emitting diodes or as organic light-emitting diodes (OLEDs). Such light-emitting elements are usually deposited onto a substrate and encapsulated with a cover.
FIG. 1 shows a conventional encapsulation used in particular for OLEDs devices. The device includes a substrate SU, on which a light-emitting element LE, e.g., a flat OLED, is located. Using an elastic sealing and adhesive compound DM, a flat, solid cover AD is glued on top of this configuration. A light-emitting element with such encapsulation has the advantage that the light-emitting element and the cover are scalable, i.e., they can be configured to any size. In addition, the encapsulation is not compressible and therefore generally insensitive to pressure. The weak points of this encapsulation, however, are the boundary surfaces leading to the OLED between the cover and the substrate, along which paths for the diffusion of oxygen and/or moisture are created, which may corrode susceptible OLEDs. Mostly affected by oxygen and moisture are either the metallic electrodes or the organic functional layers.
In addition, larger devices with a diagonal diameter of more than five centimeters and with a thin material thickness, e.g., up to 0.7 millimeters, for example, have a degree of flexibility, which may not provide a sufficiently tight connection between the different material layers, and therefore lead to corrosion or damage. Additional harmful effects may be caused in the event of temperature changes or changes in air pressure as may be the case during transportation in airplanes. As a result, the adhesive or sealing compound DM may delaminate or the substrate, which is usually made of glass, may break.
FIG. 2 shows another conventional encapsulation used in particular for OLEDs. In contrast to FIG. 1, FIG. 2 shows a cover AD having a clearance above the light-emitting element LE, therefore covering the component without touching it. The cover is seated all around the substrate SU and joined to it with a sealing compound DM. The sealing compound DM is here limited to a bearing area of the cover, which here is the same as the sealed section. Furthermore, the inside of the cover may have, at a distance from the light-emitting element a getter material GE, which is able to absorb and/or bind oxygen and/or moisture. This prevents damage to the OLED should harmful substances enter the device. In this embodiment, the edges of the encapsulation are protected better due to the absence of a straight diffusion path between adjacent boundary layers leading to the OLED, allowing a longer lifecycle for the encapsulated light-emitting element. However, this type of package has the disadvantage that the self-supporting cover becomes increasingly sensitive to compression as the surface area increases, and therefore sensitive to mechanical or ambient air pressure, which may result in the direct contact of the getter material with the OLED or the damages associated with the configuration in FIG. 1. The encapsulation according to FIG. 2 is therefore not suited for light-emitting elements with a large surface.